Dyeing with 3, 4-thiolanedithione



Patented July 18, 1950 UNITED STATES DYEIN G WITH 3,4-THIOLANEDITHIONEPhilip D. Caesar, Champaign, 111., assignor to Socony-Vacuum i! Company,Incorporated, a

corporation of New York Application November 8, 1947, Serial No. 784,927

No Drawing.

Claims.

This invention relates to, a method of dyeing fabrics and, moreparticularly, is directed to a fabric dyed witha new sulfur-containingdye.

In. co-pendlng application Serial Number 721,453, filed January 10,1947, h e is described a. new .orga-no-sulfur compound and a method forsynthesizing the same. This compound is char-- acterized by theempirical formula CrHiSs and a boiling point. of 12 0-l 25 C. at apressureof 2 millimeters of mercury. More recent investiga.- tions haveshown this compound to be 3,4-thio lanedithione, having the followingstructure:

1 s=o o=s It has now been discovered that the above compound is anexcellent dye, capable of imparting a characteristic color to articlestreated therewith under the conditions hereinafter set forth.

In accordance with the present invention, it has been found thatalkaline solutions of 3,4-thiolanedithione are colored deep purple andthat materials immersed therein, exposed to an oxidizing atmosphere anddried, are dyed a fast, characteristic reddish-brown color.

The process of this invention is particularly applicable for dyeingfabrics of animal origin, such as wool and silk. It is, however, withinthe purview of the present invention to dye other fabrics, includingthose of cellulosic nature, such as cotton or linen. While the dyedescribed herein will generally be employed for coloring tex tiles ofthe various types, it is also contemplated that 3,4-thiolanedithione canbe used to color leather, leather substitutes, paper, cellophane,paints, inks, shoe polishes and other materials where color isconsidered to be a desirable 'attribute. As is well recognized, dyeingis a varied and complex art. The technique employed is dependent on theparticular substance being 001- ored, and in treating each of the abovementioned materials, it is to be realized that the particular proceduralsteps involved in each instance will vary with the class of materialbeing dyed.

In the case of wool and silk, which consist of proteinoid fibers, it hasbeen found that direct immersion of the material into an alkalinesolution of 3,4-thiolanedithione, removal of the material from saidsolution, and subjection of the treated material to an oxidizingatmosphere gives, after drying, a finished, fast-colored reddishbrownfabric. In the case of cotton, linen and other fibers of vegetableorigin, it is a necessary prerequisite to immersion of the material inthe 2 3,4.-thiolanedithione bath that it firstbe treated with a chemicalfixingagent such as Turkey-red oil, tannic acid fixed on the fiber withtartar emetic, and others in order to. insure a final fast color.

Preparation of the dye bath is effected? in accordance with theprovisions of the present invention by dissolving 3,4-thiolanedith-ionein hot alkali. The particular alkali employed: will generally begoverned by economic factors and usually will be a hydroxide of analkali or alkaline earth metal, suitably sodium, potassium or calciumhydroxide. The dissolution process can begreatly increased by theaddition to the alkaline solution of a reducing agent such as zinc dustor sodium hydrosulfite. Accordingly, the dissolution bath is preferablyone of alkaline-reducing agent;

The fabric to be dyed is immersed in the alkaline solution generally ata moderatel-y'elevated' temperature of between about 50 F. and-about 250F. Higher temperatures, as a rule, are detrimental; After dyeing, thematerial must be-sufirciently oxidized tofully developthe color; To"bring about the desired oxidation, the fabric, after" removal from thealkaline bath, is subjected to an oxidizing atmosphere of air or'otheroxygencontaining gas, or the oxidizing atmosphere may consist of aseparate bath of a mild oxidant such as aqueous solutions of sodiumbichromate or sodium perborate, into which th fabric, after treatment inthe alkaline reducing bath of 3,4- thiolanedithione, is immediatelyconducted. The fabric, after treatment with an oxidant, is dried to givethe final dyed product. If desired,

after the oxidation step but prior to drying, the

cloth may be treated with various improving agents such as formaldehydeand the like.

The process of this invention may be either carried out batchwise or incontinuous fashion. In the latter operation, a sheet of the fabric tovbe dyed is continuously immersed in an alkaline solution of the3,4-thiolanedithione, removed therefrom, and passed through an oxidizingmedium which may either be a separate bath of a mild oxidant or anoxygen-containing gas and, if necessary, thereafter continuously passedthrough a drying area and removed by winding on cylinders or othersuitable means.

The following specific examples will further serve to illustrate themethod of the present invention:

Example I Twenty parts by weight of 3,4-thiolanedithione were dissolvedin parts by weight of an aqueone solution of 20 per cent sodiumhydroxide maintained at a temperature of 212 F. over a period of about 6hours to give a deep purple solution. A piece of wool fabric wasimmersed in this solution, removed therefrom and then immersed in a bathcontaining a mild oxidant consisting of an aqueous solution of per centby weight ofsodium bichromate. The fabric, after removal from theoxidant bath, was dried and was found to have a fast, reddish-browncolor which, when exposed to sunlight over a period of 2 weeks, stillremained fast.

Example II Twenty parts by weight of 3,4-thiolanedithione were dissolvedin an aqueous alkaline reducing solution containing parts by weight ofsodium hydroxide and 20 parts by weight of sodium hydrosulfitemaintained at a temperature of 212 F. for a period of two hours to givea deep purple solution. A piece of wool fabric was immersed in thissolution, removed therefrom and then immersed in a bath containing amild oxidant consisting of an aqueous solution of 5 per cent by weightof sodium bichromate. The fabric, after removal from the oxidant bath,was dried and was found to have a fast reddish-brown color which, whenexposed to sunlight over a period of 2 weeks, still-remained fast.

Example III Twenty parts by weight of 3,4-thiolanedithione weredissolved in an aqueous alkaline reducing solution containing 20 partsby weight of sodium hydroxide and 50 parts by weight of zinc dustmaintained at a temperature of 212 F. for a period of two hours to givea deep purple solution. A piece of wool fabric was immersed in thissolution, removed therefrom and then immersed in a bath containing amild oxidant consisting of an aqueous solution of 5 per cent by weightof sodium bichromate. The fabric, after removal from the oxidant bath,was dried and was foundto have a fast, reddish-brown color which, whenexposed to sunlight over a period of 2 weeks, still remained fast.

From the above examples, it will be seen that 3,4-thiolanedithione is anexcellent, fast dyestufi. It will be understood that the aboveembodiments are to be considered in all respects as illustrative and notrestrictive, reference being had to the appended claims rather than tothe foregoing description to indicate the scope of the invention.

I claim:

1. A method for dyeing a fabric, comprising immersing the same in analkaline solution of 3,4- thiolanedithione, removing the treated fabricfrom said solution and subjecting the fabric to an oxidizing atmosphere.

2. A method for dyeing a fabric, comprising immersing the same in analkaline solution of 3,4- thiolanedithione, removing the treated fabricfrom said solution and subjecting the treated fabric to the oxidizingaction of air.

3. A method for dyeing a fabric, comprising immersing the same in analkaline solution of 3,4- thiolanedithione, removing the treated fabricfrom said solution and immediately thereafter immersing the fabric in anoxidant bath, removing the fabric from said bath and drying.

4. A method for dyeing a fabric consisting of proteinoid fibers,comprising immersing the same in an alkaline solution of3,4-thiolanedithione,

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Name Date Homolka July 21. 1908 Number

1. A METHOD FOR DYEING A FABRIC, COMPRISING IMMERSING THE SAME IN ANALKALINE SOLUTION OF 3,4THIOLANEDITHIONE, REMOVING THE TREATED FABRICFROM SAID SOLUTION AND SUBJECTING THE FABRIC TO AN OXIDIZING ATMOSPHERE.